Pneumatically driven nutrunner



April 29, 1969 R. F. STATES 3,440,908

PNEUMATICALLY DRIVEN NUTRUNNER Filed Aug. 4, 1966 Sheet of 2 April 29, 1969 R. F. STATES PNEUMATICALLY DRIVEN NUTRUNNER Sheet 3 of2 Filed Aug. 4, 1966 United States Patent 3,440,908 PNEUMATICALLY DRIVEN NUTRUNNER Ronald Frederick States, London, England, assignor to Desoutter Brothers Limited, London, England, a British company Filed Aug. 4, 1966, Ser. No. 570,319 Claims priority, application Great Britain, Sept. 10, 1965, 38,682/65 Int. Cl. B25b 19/00 US. Cl. 81-52.4 6 Claims ABSTRACT OF THE DISCLOSURE A pneumatically driven nutrunner provided with mounting means permitting the limited rotational movement of the tool about the axis of is ouput shaft relative to a member upon which the tool is mounted due to the reaction to torque applied by the tool with the rotational movement being utilized to operate a control valve which controls the passage of air to the tool.

The invention relates to nutrunners, that is power operated tools driven for example by a pneumatic motor for screwing down nuts, "bolts, screws and the like. Such tools are often mounted in multiple form so that, for example, a number of nuts may be run down simultaneously, and it is the object of the present invention to provide a nutrunner particularly adapted for mounting together with like nutrunners in a multiple form, and in which the maximum torque which is applied to the nut, or other member being screwed down, is automatically controlled.

The invention is directed to a nutrunner of the type having a casing, a pneumatic motor therein, an output shaft driven by the motor, and a spanner upon the output shaft for engagement upon a nut to be tightened, the improvement comprising a mounting for the nutrunner defined by two main parts, a first part rigidly attached to the casing adjacent the output shaft, a second part mounted roatable in respect of the first part about an axis coaxial with the output shaft and provided with fixing means for attachment of the second part to support means for the nutrunner, stop means upon one of the two main parts which engages movement-limiting abutments on the other of the parts for lmiiting the degree of rotational movement of the one part relative to the other part, spring abu'ment means upon each part, a spring between the abutment means for urging the parts to adopt a position where the stop means engages one of the movementlimiting abutments, a pilot valve housed in one part and ope-ratively associated with the other of the parts to open the valve when the parts move relative to one another against the action of the spring due to reaction to torque applied by the output shaft, an air supply line to the motor, a pneumatic pressure operated control valve in the air line and connected to the pilot valve, and which is closed by air from the latter to stop the motor when the pilot valve is opened at a predetermined value of torque.

The invention further consists in a multiple nutrunner having a common manifold and a common base plate between which a plurality of nutrunners of the kind set forth in the preceding paragraph are attached.

The accompanying drawings show, by way of example only, one embodiment of the invention in which:

FIGURE 1 is a front elevation of the tool,

FIGURE 2 is a plan view of the tool,

FIGURE 3 is a part section part elevation on the line 3-3 of FIGURE 2, While,

FIGURE 4 is a section on the line 44 of FIGURE 2.

The tool comprises a body portion 1, a head portion 3,440,908 Patented Apr. 29, 1969 2 and a base portion 3, with the base portion being provided with a pair of bolts 4 and 5 for attachment of the tool to a base plate 6 of the multiple mounting means, while the head of the tool is provided with a cylindrical projection 7 which engages in a pair of cylindrical bores in an air supply manifold 8.

The base of the tool is made in two main parts, an upper part 9 to which a flange plate 10 of the body portion 1 is bolted by means of bolts 11 and 12, and a lower part 13 which is bolted to the base plate 6 by the bolts 4 and 5. The two base parts 9 and 13 are rotatable relative to one another about the axis of the tool by being provided with inner flanges 1 6 and 17 respectively which engage in an annular groove in a ring like locating member 18 which acts to locate the tool accurately in relation to a bore 19 in the base plate '6 co-axially with an output shaft 20 of the tool.

It will be appreciated from the above that there is no restriction to the rotation of the upper of the two main parts relative to the two lower main parts, namely the nutrunner relative to the base plate 6 about the axis of rotation of the output shaft 20.

In a projection 21 on the lower part 13 of the base 3 there is provided a bore 22 which houses a cylindrical sleeve 23 provided with a flange 24 which determines the longitudinal position of the sleeve and providing a cavity 25 in 'which -a head 26 of a valve 27 is located. Stern 28 of the valve 27 makes a close sliding fit in the sleeve and is provided with a small bleed groove 29 to remove any excess pressure below the head 26 when the valve is required to close.

Ports 30 in the sleeve 23 lead to an annular groove 31 which is connected by a bore 32 to a pipe 33 by way of a connector 34. The cavity in like manner is connected to a pipe 35 by way of a bore 36 and connector 37.

A projection 38 on the upper part 9 is provided with a screw-threaded bore 39 into which is screwed a bolt like member 40, provided with a radial groove 41 for engagement by an adjusting tool for adjusting the pressure of a helical spring 43 and a locking nut 42. The helical spring 43 is engaged upon the reduced portion of the bolt like member while the other end of the spring engages the flange 24 of the valve sleeve.

The bolt like member 40 is provided with an axial screw-threaded bore in which is fitted a screwed member 44 which engages the end of the stem 28 of the valve 27 and has a locking screw 45, by means of which the pre cise point of opening of the valve may be adjusted and locked in position by the screw 45.

When torque is applied to a nut by way of the output shaft, reaction is developed which acts to compress the spring 43 due to relative movement the upper and lower parts of the base, and to move the valve 27 in its sleeve. When a desired torque has been reached, the valve allows air to pass from the cavity 25 to the ports 30, that is from the pipe 35 into the pipe '33, and in consequence the air supply to the motor of the tool is cut off as described below.

The pneumatic motor, gearing and other parts of the tool within the body portion 1 are not shown, and may be arranged in any desired manner. The air for operating the motor enters a longitudinal bore 46 in the projection 7 on the head portion 2 by way of cross-bores 47, the effective areas of which are controlled 'by a screw threaded plunger 48 which is locked in position by a locking nut 49. The air reaches the tool by way of a cavity 50- formed between two plates 51 and 52 constituting the upper and lower members of the supply manifold 8. This manifold is common to all tools mounted in multiple form.

The projection 7 forms an airtight rotatable fit in the bores in the plates 51 and 52 so as to allow rotation of the tool about its axis due to the reaction of the torque.

The passage of air from the bore 46 to a cavity 53 in the body of the tool is controlled by an air pressure operated valve 54, enlarged head portion 55 of which enters a cross-bore 56 against the action of a leaf spring 57, to cut off the supply to the motor when air pressure rises in the pipe 33 connected by elbow 53. When air supply is cut off by the valve 54 moving across an annulus 61, a cross hole 62, shown in FIGURE 3, is exposed to air pressure which allows air to enter the chamber at the back of the valve, and in doing so, prevents the valve returning while there is air pressure in the manifold.

The supply of air to the pipe 35 feeding the valve in the base portion of the tool is obtained by way of an elbow 59 leading from the bore 46, behind the valve 54 as viewed in FIGURE 1.

The starting of the tool together with other like tools in the multiple assembly is controlled by a master valve from the supply of air under pressure to the cavity 50. Consequently, the tools start together, but in order for the operator to be able to tell when all the tools have finished running, there is provided an electric switch 60 operated by the spring 57 on each tool connected each to a light on a control panel which lights up as each tool stops. The master valve is then closed and the valve 54 returns under the action of the spring 57, the air in the pipe 35 leaks away, as previously mentioned by way of the groove in the stem 28 of the valve 27 in the base portion. Valve 54 is thus allowed to open fully, while valve 27 is free to close when pressure is again applied to the manifold.

When the tool is set up for operation, such as for example when tightening down the head of a cylinder block of an internal combustion engine, the base plate 6 is fixed relative to the block and the tool spanner is engaged with the nut on the stud of the block. Upon the motor of the tool being started, the nut is run down the stud for some distance without hindrance, but as soon as resistance is met, a reaction is developed between the two main parts of the base which causes the projection 38 on the upper main part to move towards the projection 21 on the lower main part thus compressing the spring 43 and causing the screwed member 44 to engage the stem 28 of the valve 27 and lift the head of the valve clear of its bore thereby allowing air to pass from the cavity 25 to the ports 30. More specifically, to allow the air to pass from the pipe 35 into the pipe 33. The level of torque at which this ac tion takes place can be adjusted by screwing or unscrewing the bolt-like member 40 in its screw threaded bore 39.

It is also proposed in accordance with the invention to provide two or more valves in the base portion, each operated by a separate screw rod 44 adjustable to a different position, so that the valves are opened at different values of torque, and to provide separate piped connections to the control valve 54 so that the stopping of the tool at one of two or more way valves can be rapidly set by means of a two or more way valve.

It is to be understood that the above description is by way of example only, and that details for carrying the invention into effect may be varied without departing from the scope of the invention claimed.

I claim:

'1. A nutrunner of the type having a casing, a pneumatic motor in the casing, an output shaft driven by the motor, and a spanner upon the output shaft for engagement upon a nut to be tightened, the improvement comprising a mounting for the nutrunner defined by two main parts, a first part rigidly attached to the casing adjacent to the output shaft, a second part mounted rotatable in respect to the first part about an axis co-axial with the output shaft and provided with fixing means for attachment of the second part to support means for the nutrunner, stop means upon one of the two main parts, movement-limiting abutments upon the other of the parts engaged by the stop means to limit the degree of rotational movement of the one part relative to the other part, spring abutment means upon each part, a spring between the abutment means to urge the parts to adopt a position where the stop means engages one of the movement-limiting abutments, a pilot valve housed in the one of said parts and operatively associated with the other of said parts to open the valve when the parts move relative to one another against the action of the spring due to reaction to torque applied by the output shaft, an air supply line to the motor, a pneumatic pressure operated control valve in the air line and connected to the pilot valve, and which is closed by air from the latter to stop the motor when the pilot valve is opened at a predetermined value of torque.

2. The nutrunner as claimed in claim 1, in which the force of the spring is adjustable to vary the predetermined value of torque.

3. The nutrunner as claimed in claim 1 in which said two main parts of the mounting each has a projection, with said pilot valve being a poppet valve housed in one of the projections and the other projection carrying an adjustable screw threaded valve operating member which opens the valve and passes air to the control valve to close such valve when one projection moves towards the other projection an adjustable amount.

4. The nutrunner as claimed in claim 1 in which the spring is positioned co-axially with the pilot valve, with one end of the spring abutting an adjustable screw threaded abutment member.

5. The nutrunner as claimed in claim 1 further including a head adapted to make an hydraulic connection with a manifold by way of which air is supplied to the tool.

.6. The multiple pneumatically driven nutrunner having a common manifold and a common base plate between which a plurality of nutrunners as claimed in claim 1 are mounted.

References Cited UNITED STATES PATENTS 2,292,146 8/1942 Meunier 8l52.4 2,964,152 12/1960 Banner 8l52.4 X 2,953,903 9/1960 Skoog et a1. 8l52.4 X 2,952,176 9/1960 Mitchel 8l-52.4 2,796,789 6/1957 Rice 8152.4

JAMES L. JONES, 111., Primary Examiner. 

